Air separator



"April 30, 1935. T. J. sTURTEvAN-r AIR sEPARAToR Filed March 27, 1931 2 Sheets-Sheet 1 April 30, 1935. T. J. sTuR-rE-VN'I.k

AIR sEPARAToR Fild March' 27.

2 Sheets-Sheet 2 H TM im@ lo a mmf/7A .Kv s Wi .a ,m7 Y Y B Patented Apr. 3Q, 1935 r oFFlcE AIR SELPARATOR Thomas J. Sturtevant, Weilcsley, Mass., assigner to Stnrtevant Mill Company, Boston, Mass., a corporation of Massachusetts Application March 27,

1S lllairns.

This invention relates to air separators for grading materials of thetype disclosed in Letters Patent of the United States No. 1,615,558 dated January 25,1927 and 1,703,833 dated Feb- 5 ruary 26, 1929 Vas improved by features disclosed n Letters Patent of the United StatesNo. 1,788,- 361 dated January 6, 1931.

AThe principal object of this inventionis to improve the selective action of the separator within the inner drum or separating chamber, To this end a feature of the invention resides in the provision of means, which may effectively be in theform of a rotary member, acting within the upper portion of the zone of the selective action of the air currents within the separating chamber and so constructed and arranged as to increase the centrifugal effect.

The entire zone of the selective action in the separating chamber extends from where the air, moving in a closed circuit, enters at the bottom and leaves through the centralized outlet inv the head of the drum. The motion of the upward current of air is in the form of a spiral or whirlwind due to the rotating parts in the separating chamber and to the fan above. The material to be separated is centrifugally distributed into this rising current of air and is acted on by three forces, the upward action of the air current, the outward action of centrifugal force and the downward action of gravity. The resultant of these forces determines the largest particle size that passes up through the outlet on its way to the surrounding settling or collecting chamber.

The outward action of centrifugal force is highly important and'for best results should be as uniform as possible. This centrifugal action tends to collect the material against the wall of the drum which forms the separating chamber, in a more or less compacted whirling layer which 40 tends to move downward under the iniiuence of gravity and upward due to the rising air current, but because the outlet from the separating chamber always is smaller than the maximum diameter of the chamber, a whirling particle must be moved inward by the air current, against the centrifugal forces generated, in order to pass over into the collecting chamber. While separation takes place more or less in all parts of the separating` chamber the -zone close to the upper outlet is the more important, as there the air current has to move the particles of material against gravity and in addition against centrifugal forces generated by the distributor. It follows from the above that for iine and uniform work in a separator, there should be a maximum 1931, Serial No. 525,654

of centrifugal effect in the zone close to the outlet of the separating chamber where the particles of material have to move inwardly to escape from the separating chamber. For close selection provision should be made, as far as possible, to have all of the particles of material acted on uniformly. The particular object of this invention is to insure a maximum of centrifugal effect within that part of the zone of the` selective action where it is requiredfor fine and uniform l0 work.

To the accomplishment of ythis object and such others as may hereinafter appear, as will readily be understood .by those skilled in ther art,`the invention comprises the features andV combinations of parts hereinafter described and then particularly pointed out in the appended claims.`

The nature and scope of the invention will be understood from a description of the preferred embodiment thereof illustrated in the accompanying drawings, in which: y

Figure 1 is a view, in vertical section, through an air separator of the whirlwind type provided with a centrifugal agitator in the Zone of separation close to the outlet ,fromy the separating chamber;

Fig. 2 is a view, in plan of the rotary centrifugal agitator, and in section through thewall Vof the drum which forms the separating chamber;

Fig. 3 is a View, in perspective, of the preferred form and the manner of mounting an agitator blade; and

Figs. 4 and 5 show perspective views of modied forms of the agitator blades.

Referring to the drawings, the separatorshown therein as an illustrative embodiment ofthe invention comprises an outer casing l consisting of a drum having a cylindrical wall 3 closed by a fiat head 5, and having a cone 'l at the lower end thereof terminating in a discharge spout 9. Within and spaced lfrom the outer casing is an inner casing or drum. ll consisting of'a cylindrical wall i3 closed by a flat head l5 with a' centralized outlet opening l 'l therein, and having a conical shell I 9 at the lower end thereof. This inner easing is supported by brackets '2l between and secured to the walls 3 and I3.

Beneath and spaced from the conical shell I9 is a cone 23 provided with a discharge spout 25 which extends laterally through an opening in the cone 'l of the outer casing. The cone 23 is supported by plate struts 2l between'and secured to it and the cone l. A

The inner casing forms the separating chamber 33, and the annular space between the inner the upper andlower ends thereof. Vvdrivenshaft S5 is journalled in said bearings, and within the portion of the housing above the and outer casing walls 3 and I3 forms the settling or collecting chamber 35. The space between the conical shell I9 and the cone 23 serves as an inlet opening for the passage of air from the settling chamber back into the separating chamber. Located at this space is a series of adjustable vanes 3l pivctally connected to a ring 4| secured to and projecting outward from'the loweredgeof the conical shell i9 and adjusted by a hand wheel 139 all substantially as described in said Patent No. 1,788,351 referred to.

To vary the outlet opening Il in the head of the inner casing, a valve may be provided comprising a series of overlapped plates e! resting upon the head of the inner casing and connected to radial bars or handles 53 which extend outward through brackets 55 `secured to the outer casing. These handles maybe adjusted exteriorly of the outer casing in order to vary the size of theA opening. This valve may be similar to that disclosed in said patent No. 1,615,558 referredto; l i j The materials to be graded are conducted into the separating chamber through an inclined vdelivery chute 57 and through a conical feed hopper 5S depending from lthe head 5 and having a lower cylindrical neck t@ extending down through the outlet opening in thehead l5 of the separating chamber. Mounted on the head of the outer casing are a pair of channels 6i supporting a housing 63 which extends downward through the head 5 into the hopper 5st and has bearings in A vertical head 5'has a bevel gear 6l fast thereon meshing with a bevel pinion 69 on a horizontal driving shaft 1i journalled in an inner bearing carried bythe housing 63 andY in an outer bearing 'i3 carried by a transverse channel i5 bridging the channels'iil. At the outer end of the driving shaft 1I vis apulley l1 which may be driven from any suitable source of power.

The driven shaft $5 extends down from the bearingV housing centrally of the feed hopper 59-68, its lower end projecting therefrom into the separating chamber 33?. This lower end carries a distributor 1S comprisng aplate hub 8i and a plurality of downwardly iianged segmental plates83, secured to the plate hub and to each other, as is well known in this type of air separator. l I

Projecting up fromrthe margin of the distributor plate Vhub 8l are posts 8% carrying a cylindrical hub S! surrounding the cylindrical neck B0 of the feed hopper and provided with a lower horizontal flange g3 and an upper cone flange 95. Secured to the cone flange 95 are a plurality ofV oblique arms 9'! each carrying a fan blade 99. The fan rotates clockwise in a chamber H between the casing heads 5 and i5., and its blades may overlap the upper, open endof the settling chamber.

The distributor 19 is provided, as usual in this type of separator, with a circular cover or baffle lplate which may be substantially of the diameter of the distributor '49. In the present instance this conveniently is formed of four segmental sections m3 (Fig. 2) overlapped and bolted at their radial meeting edges and also screwed to the lower flange 93 of the cylindrical hub lll. In the whirlwind type of air separator illustrated the balle thus constructed is below and relatively close to the nes outlet Il, that is, it'is in the upper rather than in the lower part of the zone of the selective action or classication within the separating chamber 33.

In the operation of an air separator constructed as hereinbefore described the materials to be graded are fed to the distributor hub plate and are whirled and thrown outward therefrom under the influence of centrifugal force, the heavier particles tending' to be thrown outward against the wall of the separating chamber through the rising air currents and the lighter particles or nes being' carried upward around the distributor baflle and thence inward through the outlet and over into the settling chamber. As the upward whirling air current lifts the material in suspension into the upper acne of the separating chamber and toward its outlet, centrifugal force and gravity act to prevent particles larger than those desired from passing through the outlet. The

nes raised to the upper part of the'classication zone, or to the outer portion of thel separatingchamber, must then travel inward to escape through the outlet;`v If thecentrifugalv action. in this upper zone close to the outlet is increased then, the ineness-of .separation remaining con'- stant, a corresponding Aincrease in the power of the rising air current is established to carry only the suspended fines throughthe outlet, the larger particles being impelled in an opposite direction,

arating chamber where they may fall to bedischarged through the spout 25. A To accomplish these desired results the distributor baille, itself being'in the upper part of the classhication zone, is utilized as a support or these blades is such that the plane of their upper .1.

surfaces is close to the outlet for the fines. The blades are so proportioned and set that the 'clearance between them and the cover of the separating chamber and between their ends and wall of the separating chamber is such: that their rotai.'

tion carries them across the path of the air our# rentas it turns to pass out ofthe cover outlet. In their preferred mounting they are set to slant backward from a radial position in relation to the direction of rotation. This is not essential but some-increase in the ease of travel of particles impelled outward is observedand when so mounted material 'has more difficulty insticking to the forward faces of the blades.

An important characteristic of the agitator blades comprises a shelf, conveniently a fiange till', at the top edge projecting in the' direction of rotation. As the blades move throughthe air current the heavier particles are engaged and impelled outward and the forwardly facing, overhanging shelf along the top edge of each blade prevents any particles moving diagonally across the blades from passing over` the top edge and thus tothe nes outlet. The flanges stop the upward movement and translate it into outward movement. Thus the classification zone close to the outletv from the separator chamber, through which the suspended-lines must mcve'inward to escape, has the heavier particles hurled outward through it with greatly increased centrifugal force with the result that the selective action is greatly improved. f

Referring to Fig. 3 the preferred form of the agitator bladesld may readily be made by removing a portion of one flange of a channeliron. leaves a complete flange im along thertop edge and a partial ilange ist? at the inner or supported end of the bottom edge. This end is punched and utilized to bolt the blade to the baille plate $93.

` When not so nne a product is desired the cen'- -trifugal effect may be dinn'nished by reversing the blades which places the flanges at the bottom edge and turns backward thus permitting some of the impacted particles to travel diego# nally'across the blades because not held back so strongly by centrifugal force. .To readily permit such a reversal of position the inner portionsk of the flanges i Dl. are punched in alignment with the lower flange punchings so that either set of punchings may receive the holding bolts.

Those skilled in the art will understand that the blade or centrifugal agitator may be of any form that will tend to prevent particles from crossing the blade easily orwill constrain the particles that impact against the face to pass off at the outer end, thus subjecting the particles to a maximum centrifugal effect as the outer end of the blade travels faster than any other portion.

Thus good results have been obtained with cen-Vv trifugal agitators in the form of a channel its as illustrated by Fig. 4, or with narrower channels i built up to the maximum height permitted by the available space and bolted together through their engaged flanges, as illustrated by 5. Such a sectional centrifugal agitator permits variation of its effective surface according to the nneness of classincation that is desired. It will be observed that cach of these modified blades may be bolted to the baille in a reverse position. Y

The nature and scope of the present invention having been indicated and its preferred embodiments having been specifically described, what is claimed as new, is:-

l. A centrifugal agitator blade for air separators shaped to a channel section for one portion of its length and to an angle section for the re-v maining portion of its length. y

2. A centrifugal agitator blade according to claim l having aligned bolt holes in the twoV anges of its channel section portion for bolting in the same position either edge up.

3. An air separator, of the type described comprising a rotary distributor plate and` a rotary baille therefor within a covered casing forming.

a classification sone, said casing having a centralized top opening, and a series of blades mounted on said baille each consisting of a plurality of channel irons detaohably secured flange to flange so that each blade has one flat face and one flanged face, said blades being mounted with their anged faces forward in the direction of rotation, theheight of the blade Vbeing such that the upper channel iron substantially sweeps said top opening, and the detachability of said channel irons permitting removal of one or more to space the blades further from said top opening andY vary the selective action. Y

li. in an air separator of the type described the combination with a covered casing which denes a zone of classication having a centralized top opening and a bottom opening, a valve for varying the eniective area of said top opening, means for causing an air current to flow upward through opening, mans for distributing the material to be classified centriiugally into said zone, .and a rotary device comprisinga series of upstanding blades above the distributor close to said top force.`

5. an air separator of the type described, the

`combination with a covered casing which defines the zone oi" classification havinga centralized outlet through its cover, means for causing an air current to flow upward within said casing an through said outlet and rotary. means for distributing the material to be classified centrifuga-ily into saidrising air current, of a ro'- tary device for increasing the centrifugal eifect withinthe upper part of said zone comprising a plurality o-i'blades each flanged at its upper edge and each being set vertically with its flange directed forward 'whereby the impacted heavier particles crossing said blades from bottom to top and tending to short-circuit through said outlet intercepted by said flanges and directed outward.

in an air separator of the type described, the combination with a covered casing which defines the zone of classification having a centralized outlet through its cover, means for causing an air current to flow upward within said casing and through said outlet and rotary means for distributing the material to be classied centrifugallyinto said rising air current, of a rotary device located just below said outlet and its surrounding cover comprising a support below said o utlet and a plurality of vertically mounted blades each having an inner portion secured to said support and Aunderlying said outlet and an outer portion extending freely beyond said support and underlying said cover, there being a lateral projection at the top edge of each blade at its inner supported portion at least to intercept the upwardly rising heavier particles below said outlet and direct them outward away from said outlet and beneath said cover. l

7. ln a separator of the type described, the combination with a fan for causing air currents to now upward through the top opening of an underlying classification zone and a rotary distributing plate within said zone, of a rotary centrifugal agitator between the distributing plate and fan comprising a circular series of vertically mounted blades each having a flange along its top overhanging its forward face.

8. The invention described by claim l in which each blade of the series is mounted to slant bacl ward from a radial position in relation to the direction of rotation.

9. The invention described by claim 7 in which said openings,- adjustable vanes at said bottom a rotary baille is located within said zone above v20 built up vertically and secured together ange to prevent impacted particles from crossing the blade.

11. An air separator of the type described having a'rotary shaft within the separating chamber, a distributor including a bafe plate rotated by said shaft, and a centrifugal agitator comprising a circular series of blades mounted vertically on the upper side of said baffle plate each said blade having a ange at each longitudinal edge both overhanging the same side of the blade and punchings in both flanges at one end of the blade to provide for mounting the blade vertically either edge up.

l2. An air separator of the type described having a rotary shaft within the separating chamber, a distributor including a baffle plate rotated by said shaft, and a centrifugal agitator comprising a circular series of blades mounted vertically on the upper side of said baiile plate each said blade comprising a plurality of channel irons tonange form-ing a unitary blade havingv one at face and one multiple flanged face.

13. In an airseparator of the type described the vcombination with a cylindrical casing defining a separating chamber, a circulating fan outside said casingv to cause air currents to flow upward through said zone and through a centralized outlet in the casing top, a rotary distributor within said casing and a baille plate above said distributor dening a classification zone between it and the casing top, of a rotary centrifugal agitator comprising a series of blades mounted on the upper side of said bafe, said agitator having the plane of its upper surface close to said outlet and each of said blades extending across the edge of said outlet into the path of the air current as it turns inward under said casing top to pass out of said. outlet and slanting backward with reference to its direction of rotation from a position on a radius of said cylindrical casing.

f THOMAS J. STURTEVANT. 

